There has been an intention in the industry of mass transit vehicles to provide a vehicle body which is formed primarily of a composite material. Such composite materials generally comprise fibreglass reinforced resin sheets and often these are formed with a foam or other core layer between the sheets. The primary intention is that the structure be formed substantially wholly from such composite materials. The intention is that such materials will reduce weight and provide a superior corrosion resistance. One technique is to provide molds in which the body is shaped and formed from separate pieces which can then be connected together. However one highly desirable feature is that the structure can provide multiple different vehicle lengths to satisfy customer demands.
A number of attempts have been made for example, by Northrup Grumman Corporation's Advanced Technology Transit Bus (ATTB) North American Bus Industries (NABI) and TPI Structural Composites who provided 40 and 45 feet length “Compobus (withdrawn from the market after limited release) a proposal by ABI, a proposal by TPI Structural Composites under the trade name “Airporter”, a proposal by Stork Fokker AESP Aerospace Group, Duvedec International and den Oudsten Bussen by (FX026), and a proposal by Duvedec International. However these proposals have been put forward in a manner that does not fully address one or more of the critical market entry or performance criteria resulting in a vehicle that has limited appeal or cannot meet the rigorous performance standards dictated by the transit agencies. In Europe, where road maintenance is superior relative to North America, durability is less of a concern, and the limited recycleability of molded fibreglass uni-bodies, there has been limited interest in lightweight composite vehicles. Stork Fokker and den Oudsten Bussen by in partnership with Duvedec International created the RETX-98 which was to enter revenue service in Rotterdam, but aside from stirring momentary interest at a few shows, the Advanced Lightweight Modular (AILMO) vehicle could not save the company from bankruptcy. The Stork Fokker AILMO body technology was licensed to APT Systems in Helmond NL which was incorporated into the Phileas, which has achieved limited success, mostly in Bus Rapid Transit systems. The license for the Stork Fokker AILMO body technology is held in North America by New Flyer Industries Ltd. but this again has achieved no commercial success.
One of the defining criteria is vehicle length. The market requires vehicles under 29 feet in length, 30 to 35 feet and 40 feet and 45 feet commuters together with 60 and even 80 feet articulated vehicles. All previous attempts can be divided into two categories: one set of molds for each body length or various body lengths created by ganging modules. The multiple mold strategy of course provides a huge tooling expense. The AILMO multiple module technique is dependent on the side windows being bonded to the body, thus functioning as a structural component. This approach has inherent weaknesses, not the least of which is that North American regulations require at least 4 of the windows on a bus to open for emergency escape.
Up till now, therefore, no commercial vehicle of this type has been successfully exploited.
It will be appreciated that body structures of this type can be deployed either as a light rail vehicle or as a road vehicle and many common features can be used in both structures. There are of course significant differences which will be well known to one skilled in the art but the principle set forth in the present application can in most cases be used in both fields.
A number of prior patents have been published showing features of the above mentioned commercial attempts and showing various other arrangements by other parties interested in this field.
The following patents have been noted as having some relevance in the present field
U.S. Pat. No. 4,059,303 (Mauri) issued Nov. 22, 1977.
U.S. Pat. No. 5,042,395 (Wackerle) issued Aug. 27 1991.
U.S. Pat. No. 5,140,913 (Takeichi) issued Aug. 25 1992.
U.S. Pat. No. 5,433,151 (Ohara) issued Jul. 18 1995.
U.S. Pat. No. 5,904,972 (Tunis) issued May 18 1999.
U.S. Pat. No. 5,918,548 (Elsner) issued Jul. 6 1999.
U.S. Pat. No. 5,997,075 (Dunder) issued Dec. 7 1999.
U.S. Pat. No. 6,065,261 (Fehr) issued May 23 2000.
U.S. Pat. No. 6,237,989 (Ammerlaan) issued May 29 2001.
U.S. Pat. No. 6,685,254 (Emmons) issued Feb. 3 2004.
PCT Publication No. WO/2004/000633 and 000634 assigned to NABI published 31 Dec. 2003.
EP Application 0 622 285 published Nov. 2 1994 and assigned to GEC Alsthom Transport SA.
Mauri discloses a conventional vehicle using a fabricated frame clad by covering panels.
Wackerle discloses a rail vehicle formed from molded upper section defining the side walls and roof connected to a floor section. The connection is provided by a corner piece which is bonded into an edge piece at each edge of each molded composite panel. The composite panels are formed from exterior sheets with a honey comb core between.
Takeichi discloses a rail vehicle which is similarly constructed to the above except that it is formed in sections which are connected edge to edge along the length of the vehicle. The floor sections are formed from side beams and horizontal rails.
Ohara discloses a similar arrangement.
Tunis discloses a technique for forming large composite core structures by vacuum assisted resin transfer molding. This is not particularly directed to vehicles but provides a technique which can form the large molded sections.
Elsner discloses a rail vehicle formed by connected beams.
Dunder disclose a vehicle where panels are connected together by insertion of an edge of a panel into a channel of the structural rail.
Fehr disclose a joint between a metal sandwich panel and a metal rail which uses welding to provide a seal.
Ammerlaan discloses the arrangement of the Stork Fokker AILMO device described above which it defines as a structure formed by connected, molded side panels, roof and floor sections where the drive components for the vehicle are bolted under the aluminum honeycomb floor. It is interesting to note that in its application to the APTS Phileas, the structure required internal cross bracing not cited in the patent to achieve the required torsional stiffness.
Emmons discloses a vehicle which is primarily formed from a roof section and a floor section together with vertical beams where the roof and floor sections are formed as a sandwich panel defined by the fibre reinforced sheets and an interconnecting core.
The two PCT applications of NABI disclose a molded structure in which the body and floor are separately molded from fibre reinforced plastics material. This is substantially based on the ATTB by Northrup Grumman Corporation.
The EP application of GEC a rail car formed of composite material where there is a channel-shaped roof section and corresponding channel-shaped floor section which butt together along the side walls.